282
FXUS61 KBTV 151109
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
709 AM EDT Mon Jul 15 2024

.SYNOPSIS...
Heat, humidity, and strong scattered showers and thunderstorms are
forecast for today and tomorrow, followed by an additional chance
for thunderstorms on Wednesday. Following a cold front passage
Wednesday night, cooler and drier weather is expected for the end of
the week and into next weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 653 AM EDT Monday...Small tweaks to PoPs this morning to
account for the light showers passing through, but overall
forecast is on track for showers and thunderstorms late this
afternoon into the overnight period and hot, humid conditions
warranting a Heat Advisory in the Champlain Valley. Previous
discussion below:

An upper level shortwave set to cross the forecast area from
west to east this afternoon/evening, paired with precipitable
water values up to around 2 inches, will produce showers and
thunderstorms this afternoon and evening. Today`s forecast
heat/high temperatures 5-15 degrees above seasonable averages
will help increase instability and add fuel to the storms.
Temperatures are expected to rise into the mid-80s to lower 90s
today with heat indices in the 90s for most. The area of highest
heat indices will be the Champlain Valley, particularly
Chittenden County, VT, and Essex County, NY, southwards, where a
Heat Advisory is in effect today and tomorrow. This heat will
help allow ML CAPE values to reach 1300-2300 J/kg across the
forecast area as dew points hit the upper 60s to lower 70s.

However, modeled shear and later timing of the forcing continues to
produce doubt for how much severe weather can occur today. Most
likely areas for severe storms will be from the St. Lawrence Valley
to southern Vermont, and damaging winds would be the primary threat.
Precipitation appears most likely around 8 PM this evening to 2 AM
tomorrow morning, which would limit the amount of instability
available from surface heating. Another threat with these storms,
severe or garden variety, will be heavy rain as one hour flash flood
guidance remains 1-2 inches for many. Areas most at risk are those
across the northern tier of the forecast area, from the St. Lawrence
Valley to the Northeast Kingdom. Under thick cloud cover and humid
conditions, tomorrow night will be warm and muggy with lows in the
60s to lower 70s.

Tomorrow will be another hot and humid day with temperatures
climbing into the 80s for most, with some lower to mid 90s possible
in the southern Connecticut River Valley. Heat indices will once
again rise into the 90s for the Champlain and Connecticut River
valleys tomorrow, and we will continue to monitor the potential for
expanding the Heat Advisory to the lower Connecticut River Valley.
Showers and thunderstorms are once again expected tomorrow
afternoon/evening as another shortwave treks through the region
ahead of a cold front. Overall instability doesn`t look completely
favorable for severe weather, with up to 1000 J/kg modeled. Though
modeled shear looks more powerful tomorrow than today, and Pwats may
surge over 2 inches. Best potential for severe weather exists for
our northern New York zones, and damaging winds would once again be
the main threat. There is, however, the limited potential for severe
hail and/or a tornado. Model hodographs are indicating favorable
conditions for atmospheric rotation with potent helicity. Once
again, storms of any kind could spell trouble for areas with
saturated soils tomorrow in such a moist air mass.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 335 AM EDT Monday...Still plenty of uncertainty as to how
things will play out during this time frame, specifically with the
timing of a cold frontal passage. Showers and thunderstorms will be
ongoing early Tuesday night, with several CAMs indicating increased
activity as a shortwave quickly pushes west to east. This feature
will move to our east late Tuesday night, allowing convection to
wane. However, a cold front will follow, crossing from northwest to
southeast on Wednesday. As noted by the previous forecaster, the
question is how quickly this front and its preceding pre-frontal
trough move through our region. The latest guidance seems to
indicate that the trough will move through rather quickly, moving
through during the morning and early afternoon hours. Meanwhile, the
cold front itself lags behind, pushing through later in the day into
the overnight. So while showers and thunderstorms are expected to
develop again Wednesday afternoon, the heaviest and most widespread
activity looks to remain just to our south and east. Shear and
moisture will be ample, but CAPE will be somewhat limited by warm
air aloft and poor lapse rates. Note that the NAM continues to show
bands of high QPF due to training of strong cells, but this seems to
be the outlier, as most other guidance is more scattered and not as
organized in nature. As such, our forecast area is no longer
included in the Day 3 Excessive Rainfall Outlook from WPC. Still,
briefly heavy downpours will be possible, and trends will need to
continue to be monitored to see if the NAM`s solution holds true.
Wednesday`s highs will be cooler than those on Tuesday, generally in
the upper 70s to upper 80s. Dewpoints will still be quite
uncomfortable, especially from the Champlain Valley eastward, so
while additional heat headlines are not anticipated, persons
outdoors should still follow heat precautions.

Showers and thunderstorms will wind down Wednesday night as we lose
daytime heating and drier air moves in behind the passing cold
front. Lows will be some 5-8 degrees cooler than the previous night,
with temperatures dipping into the mid 50s to mid 60s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 335 AM EDT Monday...Fairly quiet weather is expected for the
end of the week. The upper trough will scoot overhead on Thursday,
bringing the renewed threat of showers and possibly a few
thunderstorms. High pressure will take hold thereafter, keeping the
remainder of the week dry. Temperatures will return to near (or even
slightly below) seasonal normals on Thursday, as highs will only be
in the 70s to low/mid 80s. There will be a gradual warming trend
through the period, though we`re not expecting the hot and muggy
conditions that we`ll have during the early portion of the week.
Meanwhile, nighttime temperatures will be comfortable, with lows in
the 50s to around 60.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...We`re starting the day a little showery
with variable ceiling heights, but conditions should turn drier
and VFR within the next couple of hours. We`ll then be focusing
on showers and thunderstorms late this afternoon into the
overnight hours. This will usher in a period of lowering
ceilings and visibilities, whether by heavy thunderstorms or by
mist/fog. Best chance for MVFR or lower conditions will be
07-10Z onward. Winds may pick up for a few hours this afternoon
out of the southwest 15-20 knots for New York sites, otherwise
winds will largely stay below 10 knots outside of a gusty
thunderstorm.

Outlook...

Tuesday: VFR. Chance SHRA, Slight chance TSRA.
Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA,
Slight chance TSRA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Slight chance TSRA.
Thursday Night: VFR. Slight chance SHRA.
Friday: VFR. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory from noon today to 8 PM EDT Tuesday for VTZ005-
     009-011.
NY...Heat Advisory from noon today to 8 PM EDT Tuesday for NYZ035.

&&

$$
SYNOPSIS...Storm
NEAR TERM...Storm
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Storm